Volné radikály a ateroskleróza Tuky jsou složené sloučeniny Chemickým charakterem patří k esterům Z kyselin obsahují nerozvětvené alifatické kyseliny Alkoholickou složkou je glycerol Glycerol jako trojsytný alkohol může tvořit mono-, di- a triacylglyceroly (v dřívější terminologii mono-, di- a triglyceridy) o n HO—CH2 H3C-(CH2)x-C-0-CH2 HO—CH HO-CH HO—CH2 glycerol HO-CH2 monoacylglycerol O n H3C-(CH2)x-C-0-CH2 H3C-(CH2)y-C-0-CH HO-CH2 d iacy {glycerol O II HaC-tCH^-C-O-CHz O H3C-(CH2)y-C-0-CH O II H3C»(CH2)z-C-0-CH2 triacylgiycerol The structure of a phospholipid CH2~ CH— CH2 O 0 C CH2 CH2 CH2 CH2 a> ch2 o X3 O x: Q. o CH2 CH2 CHa 0C = CH2 CH2 CH2 CH2 CH2 CH2 CH CH O CH, CH2 ■o X CH. CH, CH. CH, CH2 CH2 CH2 CH2 CH2 CH, CH3 CH3 phosphatidylcholine CHOLINE PHOSPHATE < GLYCEROL FATTY ACIDS < á (a) Structural formula (b) Space-filling model CH« . CH« "N* / ^c CH« ch- ca Membrane <-constituent Cholesterol ■> Testosterone Cortisol T Bile salts Oestradiol Figure A3. The structure of cholesterol. extracellular fluid (outside) phospholipid cytoplasm (inside) Shrnutí Potravou jsou přijímány tyto základní látky tukovité povahy: triacylglyceroly cholesterol a jeho estery fosfolipidy (především lecithin) Major Digestive Organs Mouth Tongue Pharynx Salivary Glands Esophagus Stomach Pancreas Small Intestine Large Intestine adapted from Thitradeau Healthy liver, gall bladder, duodenum, pancreas, spleen, and stomach. Gallbladder Duodenum Stomach Spleen Anatomical Chart Co., Skokie, Illinois v Štěpení tuků v tenkém střevě Enzym Substrát Optim, podmínky Konečný produkt DUODENUM pankreatická lipasa fosfolipasa cholesterol esterasa triacylglyceroly fosfolipidy (lecithin) estery cholesterolu s mastnými kyselinami soli žlučových kyselin diacylglyceroly monoacylglyceroly mastné kyseliny glycerol mastné kyseliny (lysolecithin) volný cholesterol Další oddíly tenkého střeva střevní lipasa monoacylglyceroly glycerol mastné kyseliny Triglyceride ¥ ° H-C-0-I H-C-O-" h-c-o-cAAAA Ä u u-ŕ-nw Oiglyoend« HCOHq H-C-O-C/VNA/N o H-c-o-^W\A + Fmwí Firiy And / H P-fiOfej« U/tase Acuon Fat ^'i'V X.r T-' F" h h ŕ •< r, X, p- h N X, * , Bile salts .H -K. Hydrofobní části žlučových kyselin se vnoří do tukových kapének, hydrofilní části zůstávají na povrchu, to vede ke štěpení. Čím menší kapénky, tím lepší účinek pankreatické lipázy Hydrolýza triacylglycerolů pankreatickou lipázou. Látka orlistat (Xenical) inhibuje PL - léčba obezity Li [jase Triglyceride > Monoglyceride and fatty acids Micely - malé agregáty lipidů a žlučových kyselin. Micely přilnou k povrchu epiteliálních buněk a tuky jsou absorbovány prostou difúzí nebo pomocí transportního proteinu. Mastné kyseliny a monoacylglycerolyjsou transporto vány do ER, kde jsou resyntetizovány triacylglyceroly. Poté jsou v GA tvořeny chylomikra a exocytózoujsou vypuzeny ven do lymfy. Tou se následně dostávají do krve. Bile salts Monoglyceride Fatty acids Phospholipids Cholesterol Capillary network Blood vessels Short-chain fatty acids Medium-chain fatty acids Glycerol, Protein Triglyceride Monoglyceride Micelle Chylomicron Lonvg.chajn fatty acids To liver Following uptake across the apical membrane of the enterocyte, the products of gastrointestinal (GI) lumen lipid digestion — monoglyceride (MG) and fatty acid (FA) — can either diffuse across the enterocyte and enter the portal vein blood or be re-synthesized to triglyceride (TG) by either the 2-monoglyceride (2-MG) pathway associated with the smooth endoplasmic reticulum (SER) or the a-glycerol-3 phosphate (G3P) pathway associated with the rough endoplasmic reticulum (RER). TG formed by these pathways typically enters the ER lumen and is assembled into lipoproteins (LPs; represented by orange circles). LPs are then transported to the Golgi, exocytosed from the enterocyte and taken up into the intestinal lymphatic system. As lipid contained within the lipoprotein assembly pathways and the Golgi is destined for transport to the systemic circulation by the intestinal lymphatic system, this pool of lipids is referred to as the lymph lipid precursor pool (dashed blue line). A cytosolic pool of lipids is also located within the enterocyte. This lipid pool comprises excess TG formed by the G3P pathway and endogenous lipids taken up from the intestinal blood supply in the form of either FA or chylomicron (CM) remnants. The cytosolic lipids are subject to hydrolysis by cytosolic lipase and the digestion products formed can be re-circulated into TG assembly pathways. However, the majority of lipids from this pool exit the enterocyte in the form of TG or free FA and are taken up into portal vein blood. The pool of lipids that is transported from the enterocyte by the portal vein is therefore referred to as the portal lipid precursor pool (dashed red line). Recent evidence suggests that the trafficking and pooling of lipids within the enterocyte have a significant influence on the intracellular disposition of lipophilic drugs. Porter eŕ al. Nature Reviews Drug Discovery 6, 231-248 (March 2007) I doi:10.1038/nrd2197 r LP - lipoproteinová lipáza. Stepí triglyceridy, mastné kyseliny vstřebány, zbytek bohatý na cholesterol do jater. í r, 5 ŕOlŕUSÉ TISSUE, MUSCLE .-1 _i: l /** S tissue. í uuscle VLDL - very low density lipopr )teins I DL - intermediate density lipo )rotein LDL - low density lipoprotein \_ HDL - high density lipoprotein CmETAJWFAT TR3GĽ1CE RICE rH^irA^^r, , CAPILLARY CHYLQMICflQN ■0—>©]; HbMrVŕNT he;c=ľ7tjh iNTÍSTiné FJ.FACO& LIVER CELLS ^^ J * * \ '/■ ChOLESTlEPCL ♦ V ■ ŕ V LDL HECEPTCKS A HH, >C\ CHCXE5r=ňI is clctaled. increasing the risk of atherosclerosis, tin- reason is almost alua\s an increase in «inolatin^ I.Dl.. Lipoprotein Subclasses VI.DI, 1.02 li)! LDL - Ilír Ilia, IVa- 1.06- ni»L ivh 1.20-^S* CIIVI.OMl KKMľSAYf BfAdcvHraitUhlnc Diameter (nM ) LDL RECEPTOR, a glycoprotein embedded in the plasma membrane of most body cells, was purified from the adrenal gland by Wolfgang J. Schneider in the authors' laboratory. David W. Russell and Tokuo Vamamolo cloned complementary DNA derived from its messenger RNA. The DNA's nucleotide sequence was determined and from it the 839-amino-acid sequence of the receptor's protein backbone was deduced. Sites of attachment of sugar chains to nitrogen (.V) and oxygen (O) atoms were identified, as was a stretch likely to traverse the membrane. The actual shape of the receptor is not yet known; the drawing is a highly schematic representation. v/ f O .G3 > LDL RECEPTOR / CHOLESTERYL ESTER APOPROTEIN S-100 PLASMA MEMBRANE COATED PITÍ ŕV GOLGI APPARATUS SYNTHESIS OF LDL RECEPTORS SYNTHESIS OF CHOLESTEROL RECEPTOR DNAA/SA/VN rnaaaaaa\ / inhibits P r3\ HMGCoA REDUCTASE O RECYCLING VESICLE OVERSUPPLY OF CHOLESTEROL ENDOPUSMIC RETICULUM "«Sna? «'BOSOMS ^^.. AMINO ACIDS CELL MEMBRANE. STEROID HORMONES AND BILE ACIDS , %,f\ | STORAGE OF i7'V ! CHOLESTERYL ESTERS CIRCULATING LDL (/<>/» right) is taken into a cell by receptor» mediated endocytosis. LDL is bound by a receptor in a coated pit, »»hich iuvuginatcs and piuebvs oft* to form a coated vesicle. Fusion of sc» eral vesicles gives rise to an endosome, in whose acidic environment the LDL dissociates from the receptor, which is recycled to the cell surface. The LDL is delivered to a lysosome, where enzymes break down the apoprotein /MOO into amino acids and cleave the ester bond to xield unestcrified cholesterol for membrane synthesis and other cellular needs. The cellular level of cholesterol is self-regulating. An ovcrsupply of cholesterol has three metabolic effects. It inhibits the enzyme HMG CoA reductase, which controls the rate of cholesterol synthesis (/); it activates the enzyme AC.lT. which esteri* fies cholesterol for storage (2), and it inhibits the manufacture of new LDL receptors by suppressing transcription of the receptor gene into messenger. RNA U), which would ordinarily he translated on rihn-somes of the endoplasmic reticulum to make the receptor prouin. LDL receptor na jaterních a jiných buňkách = zpětnovazebná regulace Scavenger receptor na M§ = fagocytóza bez regulace = vznik pěnových buněk = základ aterosklerozy (Brown a Goldstein - Nobelova cena) Atherosklerosa <" ather°9enese ^^ trombogenese = zúžení až uzávěr cév. Nemá jedinou příčinu (> 200), více spolupůsobících faktorů: „Abnormální" lipidy, hypertense, nikotin, DM, hypercholesterolemie, genetické dispozice, faktory srážení krve, homocystein, ... Cévní endotel Klíčové postavení v ochraně cévní stěny před atherosklerotickými změnami - Kontrola permeability - Kontrola optimálního průtoku - Zajištění nesmáčivosti povrchu (zabránění adheze a agregace trombocytů) - Aktivace koagulace - Kontrola fibrinolýzy, angiogeneze Působení endote aclheze koagulace fibrinolýza leukocytu ao něze a agregace trombocytu cévní tonus regulace proliferace buněk hladké svaloviny stabilizace makrofágů cévní permeab:lita O nativní LDL 0oo o o cévního endotelu O O °o oxidace LDL Modifikace LDL • Přímá oxidace apoproteinu B a PL • Vazba aldehydu na aminoskupinu Lys (glc, malondialdehyd) - glykace usnadňuje oxidaci LDL =^> oxidace glykovaných bílkovin vede k tvorbě AGEs (advanced glycation end-products) • Vícemodifikované LDL nejsou rozpoznávány LDL receptory (pohlcovány makrofágy a ukládány v podobě kapének =^> pěnové buňky Dalších 5 obrázků Tür K E W E N CJ LA K1 D J QU RN A L af M E D Kľ [ K K RHVI HW ARTICLH MECHANISMS OF DISEASE Inflammation, Atherosclerosis, and Coronary Artery Disease Goran K. Hansson, M.D., Ph.D. Figure 1. Atherosclerotic Lesion in a Human Artery. Panel A shows a cross-sectioned coronary artery from a patientwhodiedofa massive myocardial infarction. It contains sn occlusive thrombus superimposed on a lipid-rich atherosclerotic plaque. The fibrous cap covering the lipid-rich core has ruptured (area between the arrows), M'crobes> autoantigens, exposing the thrombogenic cote to the blood. Trichrome stain was used, rendering luminal tirombus and intraplaque hemorrhage red and ™ collagen blue. Panel B is a high-power micrograph of the area in Panel A indicated by the asterisk and shows that the contents of the atheromatous plaque have seeped through the gap in the cap into the lumen, suggesting that plaque rupture preceded thrombosis (the asterisk indicates cholesterol crystals). (Panels A and B courtesy of Dr. Erling Falk, University of Aarhus, Aarhus, Denmark.) Panel C illustrates the consequences of the activation of immune cells in a coronary plaque. Microbes, autoantigens, and various inflammatory molecules can activate T cells, macrophages, and mast «lis, leading to the secretion of inflammatory cytokines (e.g., interferon-y and tumor necrosis factor) that reduce the stability of plaque. The activation of macrophages and mast cells also causes the release of metalloproteinases and cysteine proteases, which directly attack collagen and other components of the tissue matrix. These cells may also produce prothromboticandprocoagulant factors that directly precipitate the formation of thrombus at the site of plaque rupture. Co roň-i ry artery Figur« 2. Activating; Effect of LDL Infiltration on Inflammation in the Art-err. In patients wich hypercholesterolemia, excess LDL infiltrates the artery and is retained in the intinia, particularly at sites of hemodynamic strain. Oxidative and enzymatic modifications lead to the release of inflammatory lipids that induce endothelial cells to express leukocyte adhesion molecules. The modified LDL particles are taken up by scavenger receptors of macrophages, which evolve into foam cells. Coronary artery Figure 3- Role of Macrophage Inflammation of the Artery- Monocytes recruited through the activated endothelium differentiate into macrophages. Several endogenous and microbial molecules can ligate pattern-recognition receptors [toll-like receptors) on these cells, inducing activation-and leading to the release of inflammatory cytokines, chemokines, oxygen and nitrogen radicals, and other inflammatory molecules and, ultimately, to inflammation and tissue damage. Adhesion Migration l ledum Endotoxins, heat-shock proteins, oxidized LDL, others Inflammation, tissue damage Toll-like receptor Inflammatory cytokines, chemokines, proteases, radicals i______________________________i Coronaiy arteiy Figure 4. Effects of T-Cell Activation on Plaque Inflam mat km. Antigens presented by macrophages anddendriticcells (antigen-presenting cells) trigger the activation ofantigen-specificTcells in the arteiy. Most of the activated T cells produce Thl cytokines (e.g., interferon-?), which activate macrophages and vascular cells, leading to inflammation. Regulatory T cells modulate the process.by secreting antiinflammatory cytokines (such as inter-leukin-10 and transforming growth factor ß). Antigens: oxidized LDL, heat-shock proteins, microbes Zdravý člověk Tkáňová buňka Receptor LDL Receptor acetyl-LDL Makrotág Těžká forma rodinné hypercholesterolémie LDL * = , ' Kapky cholesterolu Tkáňová buňka Makrotág Monocyt/makrofág LDL Media Malrofág a) Trombocyly Rozpadové zbytky Trombocyty Hladká svalová buňka b) Makrofágy Makrofágy C) Rozpadové zbytky Změněná hladká svalová buňka Tromboxan Proslacyklin Volné trombocyttl Endolel 'Ulpívající Irombocyly _________H Volné Irombocyly Endolel Table 2 -Initial Classification Based on Total Cholesterol and HDL Levels* Cholesterol Level Initial Classification Total Cholesterol Desirable blood cholesterol Borderline high blood 240 mg/dl (6.2 mmol/L) or greater High blood cholesterol HDL Cholesterol < 35 mg/dl (0.9 mmol/L) Low HDL cholesterol *HDL indicates high-density lipoprotein < 200 mg/dl (5.2 mmol/L) 200-239 mg/dl (5.2-6.2mmol/L) cholesterol Terapie vysoké hladiny cholesterolu ©©O LDL IN PLASMA 1 LDL UPTAKE 2 SYNTHESIS / HMGCoA / ^ CHOLESTEROL \ BILE ACIDS «^" LIVER CELL INTESTINE J RECYCLING BILE ACIDS ~1h M © ® © 1 HMGCoA / CHOLESTEROL BILE ACIDS WMĚm^ -v i HMG CoA ^^ BLOCKED. 5Y ENZYME | CHOLESTEROL 'N'H,SlTOR BILE ACIDS t RECYCLING ^m BLOCKED " C RECYCLING BLOCKED A M LIVER GETS CHOLESTEROL for conversion into bile acids from IDL and LDL taken up from the circulation (/) or by synthesizing it de novo (2). A key step in the long synthetic pathway is reduction of H.MG CoA to mevalonic acid, a reaction catalyzed by the enzyme HMG CoA reductase. The enzyme is inhibited by the drugs com-pactin or mcvinolin, whose side chain is so similar to that of HMG CoA (colored frames) that it blocks the enzyme's active site. Enzyme inhibition leaves liver dependent on uptake of IDL and LDL. Food guide pyramid Fats, Oils, Sweets (Use sparingly) Milk, Yogurt, Cheese (2-3 servings) Vegetables (3-5 servings) Key o Fat (naturally occuring and added) Sugars (added) These symbols show fát and added sugars In foods. Meat, Poultry, Fish, Dry Beans, Eggs, Nuts (2-3 servings) Fruit (2-4 servings) Bread, Cereal, (6-11 servings) dietary recommendations Eat plenty of fresh fruit and vegetables, at least five different portions per day. Minimize intake of fats and red meats, but do not become paranoid about it. Don't worry about polyunsaturates versus saturates. Check your cholesterol level. If 200 mg/100 ml or below don't worry. If at or above 250 mg/100 ml seek medical advice. Consume no more than 300 units (200 mg) of vitamin E (d-a-tocopherol, not dl-a-tocopherol) per day from a reliable source such as the 'own brand' of a reputable chain drug store. Take with food as you need fat to absorb it. If you wish, consume up to 250 mg of vitamin C per day. Again, select a reputable supplier (e.g. the 'own brand' of a reputable chain drug-store). If you smoke, stop. If you can't, eat plenty of fruits and vegetables and consider supplementing with more vitamin C (Table 2, p. 67). Do not take any form of iron supplements unless there is a clearly identified medical need monitored by laboratory tests. We see no case at present for consuming /^-carotene supplements. Table 2. Recommended dietary allowances (RDAs/ or Reference Nutrient Intakes (RNI) for various nutrients (values are quantities needed per day to meet the known nutritional needs of healthy persons) UK USA Males Females Males Females Vitamin A 700 [ig 600 ng 1000 ng 800 fig Vitamin E* >4 mg >3mg 10 mg (15 IU) 8mg Vitamin C* 40 mg 40 mg 60 mg 60 mg j8-Carotene not set not set not set not set Selenium 75 jig 60 jig 50-200 ng Iron 8.7 mg 14.8 mg 10 mg Zinc 9.5 mg 7.0 mg 15 mg Copper 1.2 mg 1.2 mg 2-3 mg Fibre 12-14 g 20-35 g Vitamin C - test tube experiments - also pro-oxidative properties. Why do these pro-oxidant effects of ascorbic acid not usually happen in vivo? Because under most circumstances free iron and copper are not available in the extracellular fluids. Positive Risk Factors Age Male 45 or older Estrogen Status Female 55 or older (or premature menopause) without estrogen replacement therapy Family history of premature CHD definite myocardial infarction or sudden death before 55 y of age in father or other first-degree relative Current cigarette smoking Hypertension blood pressure 140/90 or greater** or taking antihypertensive medication Low HDL cholesterol 35 mg/dl [0.9 mmol/L] or less** Negative Risk Factors*** High HDL cholesterol (60 mg/dl [1.(5 mrnoI/L] or greater) Peripheral Arterial Disease Carotid artery (To the body) Superior mesenteric artery & Celiac artery (Intestines) Renal arterv (Kidneys) Narrowed Artery Ischemia-decreased oxygen-nch blood to an area, which can cause pain and dysfunction. Normal Layers of Artery Adventilia Media Intima Arteries become narrowed and blood flow decreases in arteriosclerosis Buid up of fatly substances in the wal of the arten/ tfADAJVL Atherectomy For more info,. rltbáilLvuit-rUniimé